Dehumidification systems are required for spaces and facilities in which humidity levels must be controlled to an acceptable level. Often systems are configured to utilize a refrigeration system in which an evaporator coil is used to remove moisture from the air and a downstream condensing coil is used to reheat the dehumidified air, which can then be delivered to a space. In some applications, these types of systems are utilized in conjunction with a desiccant wheel to aid in regenerating the wheel. However, the air used for the regeneration process is often ambient air which is subsequently exhausted from the system. One known system is disclosed in U.S. patent application Ser. No. 12/870,195 filed on Aug. 27, 2010 entitled High Efficiency Desiccant Dehumidifier, the entirety of which is incorporated by reference herein. Although satisfactory dehumidification performance can be achieved in systems incorporating a refrigeration system and a desiccant wheel, operating costs can be relatively. This is especially true for systems requiring supplemental heating of outdoor air to achieve satisfactory regeneration temperatures. Improvements are desired.